A person may not disturb the ground within 100 feet of a burial ground for the purpose of excavating or covering over the ground or erecting, altering or repairing any structure without having a development plan approved by DHPA
Before beginning to probe, repair all possible stones with pieces found in the cemetery. The piece missing might simply be stacked in the corner of the cemetery.
The probe should be solid-tipped and be blunt-ended; no hollow-core probes. Do not use longer probes as they may penetrate the coffin chambers and contact human remains. Despite common belief, historic graves are rarely as deep as six feet.
Create a systematic probing approach; random probing will not help find stones.
Identify the most likely place there were stone would be located (i.e. near the head of the grave).
Have an understanding of grave orientation. Most historic graves are oriented east-west with the head to the west.